Information and communications technologies (ICTs) have enabled the rise of so-called “Collaborative Con- sumption” (CC): the peer-to-peer-based activity of obtaining, giving, or sharing the access to goods and services, coordinated through community-based online services. CC has been expected to alleviate societal problems such as hyper-consumption, pollution, and poverty by lowering the cost of economic coordination within communities. However, beyond anecdotal evi- dence, there is a dearth of understanding why people participate in CC. Therefore, in this article we investigate people’s motivations to participate in CC. The study employs survey data (N = 168) gathered from people reg- istered onto a CC site. The results show that participa- tion in CC is motivated by many factors such as its sustainability, enjoyment of the activity as well as eco- nomic gains. An interesting detail in the result is that sustainability is not directly associated with participa- tion unless it is at the same time also associated with positive attitudes towards CC. This suggests that sus- tainability might only be an important factor for those people for whom ecological consumption is important. Furthermore, the results suggest that in CC an attitude- behavior gap might exist; people perceive the activity positively and say good things about it, but this good attitude does not necessary translate into action.